The present invention relates to an HVAC system wherein an ordered record of faults occurring across the system is maintained at a single display location.
Typically, a heating, ventilating, and air conditioning (HVAC) system includes multiple components installed in a building and functioning together in a coordinated manner. Normally, an HVAC system includes an indoor unit (gas furnace or fan coil), an outdoor unit (A/C or heat pump), and a thermostat. Further, more sophisticated systems might have a multi-zone control capacity including a zone control and zone dampers. HVAC systems also frequently include accessories such as filters, humidifiers, and ventilators.
The operation of these multiple units is highly inter-dependent. A problem at one unit may cause a consequent malfunction at another. As an example, a clogged air filter on a blower can cause furnace airflow reduction, which can cause a furnace high temperature limit to trip. The net result from a homeowner's viewpoint is simply a lack of sufficient heat supply.
During a cooling season, the same clogged filter and consequent reduction in airflow can cause the air conditioning coils to freeze up, which may potentially damage the air conditioning compressor.
Across the many possible combinations and inter-relationships of an HVAC system, there are many other examples of such cause and effect relationships. A service technician coming to a building in response to a problem typically begins with no specific lead as to what the actual problem may be. Sometimes, a reported symptom does not re-occur when the technician is present because conditions may have changed. Even if the technician does observe the symptom, a root cause may be elsewhere within the system.
Thus, technicians typically rely on past experience and guesswork to determine the location of the necessary repair. Frequently, this may result in an improper diagnosis of a problem with the system, and potentially repeated unnecessary replacement of parts in an attempt to correct the system function. This process is unnecessarily time-consuming and costly.
Conventional HVAC systems have not had system-wide fault recordation. Individually, some high-end HVAC components, such as variable speed gas furnaces, maintain an individual fault record for the component itself. While this is somewhat effective, individual component fault records do not pinpoint identification of root problems, and the consequent cause of a subsequent problem.
Accordingly, it is desirable to provide an ordered fault list at a central location within an HVAC system that assists a technician with heretofore unavailable historical data to increase understanding of the faults over a historical time period and permit a relatively rapid diagnosis of the problem source.